Control system



Mar. 13, 1923. 1,448,381

- E. M. BOUTON CONTROL SYSTEM Filed Maw 12, 1919 WITNESSES: INVENTOR Jiggar Bot/fan Patented Mar. 13, 1923.

UNITED STATES PATENT OFFICE.

EDGAR M. BOUTON, OE WILKINSBURG, PENNSYLVANIA, ASSIGNOR TO WESTINGHOUSEELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

CONTROL SYSTEM.

Application filed May 12, 1919.

To all whom it may concern.

Be it known that I, EDGAR M. Bouroia, a citizen of the United States,and a resident of lVilkinsburg, in the county of Allegheny and State ofPennsylvania, have invented a new and useful Improvement in ControlSystems, of which the following is a specification.

My invention relates to reversing systems for electric motors and it hasfor its object the provision of a reversing system that shall beparticularly adapted for push-button control.

According to the present invention, the motor may be started in eitherdirection upon the actuation of one of two push-buttonswhich effect theclosing of one or the other of two reversing contactors. The pushbuttonsmay then be released, the contactor coils being maintained energized byholding circuits comprising switches mechanically connected to the openreversing contactor-s and protective resistors. The commonly employedadditional mechanically connected switches are thereby done away withand the use of the resistors avoids difficulties in operation due to thecounter-electromotive force of the II10tOI,',&S will hereinafter beexplained.

The accompanying drawing is a diagrammatic view of circuits andapparatus embodying my invention.

An electric motor, having an armature 1 and a shunt field-magnet winding2, is connected between line conductors 3 and 4, the armature 1 beingconnected in series with an accelerating resistor 5. The resistor 5 isadapted to be short-circuited by a contactor 6 having a coil 7 that isadapted to be energized by the counter-electromotive force of the motor.The direction of operation of the motor is determined by a pair ofreversing contactors 8 and 9 having energizing coils 10 and 11,respectively, the circuits of which are adapted to be initially closedby start push-button switches 12 and 13 and which may be opened, at anytime, by a stop push-button switch 14. The reversing contactors 8 and 9are supplied with contact members 15 and 16 which are open when thecorresponding reversing contactors are closed and closed when thecorresponding reversing contactors are open. The contact members 15'and16 are adapted Serial No. 296,615.

to close a dynamic-braking circuit comprising the armature 1 and adynamic-braking resistor 17 A pair of resistors 18 and 19 are connected,in parallel, between the line conductor 4 (through the start push-buttonswitches 12 and 13, respectively,) and a terminal 20 of thedynamic-braking resistor 17.

Assuming that it is desired to start the motor in the forward direction,the start push-button switch 12 may be actuated, whereupon a circuitwill be completed from the line conductor 3, through the stoppush-button switch 14, the coil 10 and the start push-button switch 12,to the line conductor 4. The coil 10 becoming thus energized, willeffect the closing of the contactor 8, whereupon the circuits of themotor will be established for operation, in the forward, direction, fromthe line conductor 3 through the accelerating resistor 5, the lowermember of the reversing contactor 8, the armature 1 and the upper memberof the reversing contactor 8, to the lineconductor 4. When thecounter-electromotive force of the motor attains a predetermined value,the coil 7 will become sufliciently energized by the circuit extendingfrom one terminal of thearmature 1, through the lower member of thereversing contactor 8, the coil 7, the dynamic-braking resistor 17 andthe contact members 16, to the other terminal of the armature 1, toelfect the closing of the contactor 6 and the consequentshort-circuiting of the accelerating resistor 5.

The above. operation has been described upon the supposition that thestart pushbutton switch 12 has been maintained in its actuated position.The operation will be substantially the same, however, if, after theinitial operation of the start pushbutton switch 12, it be immediatelyreleased for, upon the closing of the reversing contactor 8, a holdingcircuit for the coil 10 becomes established from the line conductor 3,through the stop push-button switch 14, the coil 10, the resistor 18,the contact members 16 and the upper member of the reversing contactor 8to the line conductor 4..

without the aid of any mechanically connected switches additional tothose requirec for effecting dynamic-braking.

To stop the motor, the stop push-button switch 1 1 may be actuated tobreak the circuit of the coil 10, whereupon the reversing contactor 8willfall open by gravity, incidentally effecting the closing of thecontact members 15. The dynamic-bral-zing circuit becomes thereuponestablished for the motor from one terminal of the armature 1, throughthe contact members 15, the resistor 17 and the contact members 16, tothe other terminal. of the armature 1.

To start the motor in the reverse direction, the start push-buttonswitch 13 may be actuated. The operation is substantially the same asthat above described except that the holding circuit of the coil 11comprises the dynamic-braling resistor 17. The ohmic value of thisresistor is so low as not materially to affect the operation. On theother hand, the circuit of the coil 7, which formerly comprised theresistor 17, now excludes that resistor.

The resistors 18 and 19 are so designed as to maintain the coils 10 and11 energized to such degree that the contactors 8 and 9 may remainclosed when they have become closed, but not to effect the closing ofthe contactors in the first instance. Otherwise,

the coils 10 and 11 would become simultaneously sufficiently energizedto effect the actuation of both contactors 8 and 9 upon the actuation ofeither push-button switch By means of the above-described arrangement ofcircuits, I am enabled to effect-the push-button control of a motorwithout the employment of more switches than are required without suchcontrol, and without fear of the coils 10 and 11 being maintainedenergized by the counter-electromotive force of the motor upon theactuation of the stop push-button switch 14;

Modifications within the spirit and scope of my invention will obviouslyoccur to those skilled in the art and are intended to be covered by theappended claims.

I claim as my invention:

1. The combination with an electric motor and a pair of reversingswitches therefor, each having an actuating coil, of means for initiallyenergizing said coils, a pair of resistors and a pair of switchesrespectively associated with said reversing switches, said pair ofswitches being open when the associated reversing switches are closedand being closed through the one or the other resistor when theassociated reversing switches are open for maintaining energized thecoils of the reversing switches with which they are not associated aftersaid initial energization ceases.

2. The combination with an electric motor,

a pair of reversing switches therefor, each having an actuating coil,and a pair of switches for dynamically braking said motor, of a pair ofswitches for initially energizing said coils, and a pair of resistors,each of said dynamically-bralring switches being adapted to connect thecoil of one of said reversing switches in circuit with one of saidresistors to maintain said coil energized.

3. The combination with an electric motor having an armature, a pair ofreversing switches for said motor, each having an actuating coil, adynamic-braking resistor, and a pair of switches mechanically connectedto said reversing switches for connecting said. dynamic-braking resistorinto circuit with said armature, of a pair of switches for respectivelyenergizing said coils initially, a pair of resistors, and means forconnecting one of said reversing switches, its actuating coil, theswitch mechanically connected to the other reversing switch and one ofsaid pair of resistors in series to maintain said actuating coilenergized.

4:. The combination with a dynamo-electric machine, and a plurality ofswitches for governing different operations thereof, each switch havingan actuating coil, of means for manually energizing the one or the otherof said coils temporarily, a plurality of auxiliary switches actuatedoppositely to the movements of said governing switches, a plurality ofresistors and means comprising said auxiliary switches for maintainingenergized through one or another resistor the coils of the governingswitches with which they are not associated subsequent to the cessationof such manual energization.

5. The combination with an electric motor and a pair of reversingswitches therefor, each having an actuating coil, of aplurality ofpush-buttons biased to the open position and adapted when closed toenergize the one or the other of said coils, a plurality of resistorsand a plurality of switches respectively associated with said re versingswitches to close through one or another of said resistors when theassociated reversing switches are open for maintaining energized thecoils of the reversing switches with which they are not associated afterthe active push-button is released.

6. The combination with an electric motor, a plurality of reversingswitches therefor, each having an actuating coil, and means fordynamically braking said motor, of means for initially energizing theone or the other of said coils, and a plurality of translating devicesrespectively adapted to be connected through a portion of saiddynamicbraking means and the coil of one of said reversing switches tomaintain that coil energized. V

7. The combination with an electric motor, and a plurality of reversingswitches therefor, each having an actuating coil, of means for initiallenergizing the one or the other of said coi s, and a plurality oftranslating devices respectively adapted to be connected through acontact-making portion of one reversing switch and the actuating coil ofanother immediately upon said means becoming inoperative to maintainthat coil energized.

8. The combination with an electric motor, and a plurality of reversingswitches there- EDGAR M. BOUTON.

